Squid-inspired packaging: Scientists create thermoregulating material for F&B packs

11 Apr 2022 --- Engineers at the University of Irvine, US, have invented a packaging insulator material inspired by squid skin. The design could, in future, keep beverages hot and protect other products by regulating heat through reconfigurable metal structures that can reversibly separate from one another and come back together under different strain levels.

The research, published in Nature Sustainability, sought to replace the metalized polymer films widely used for packaging, which feature static infrared reflecting properties, with “green and low-cost alternative materials” that have desirable dynamic thermoregulability.

Alon Gorodetsky, UC Irvine associate professor of chemical and biomolecular engineering, and his team, mimicked the composition of cephalopod skins such as squid, octopus and cuttlefish.

“The metal islands in our composite material are next to one another when the material is relaxed and separated when the material is stretched, allowing for control of the reflection and transmission of infrared light or heat dissipation,” explains Gorodetsky.

“The mechanism is analogous to chromatophore expansion and contraction in a squid’s skin, which alters the reflection and transmission of visible light.”

Squid skin inspired material could in future be used for hot and cold packaging products.Squid game
Chromatophores – organs present in the skin of many cephalopods – change their size to help squids communicate and camouflage their bodies to evade predators and hide from prey. Gorodetsky says by mimicking this mechanism, his team has enabled “tunable thermoregulation” in their newly invented material, which can lead to improved energy efficiency and protect sensitive fingers from hot surfaces.

A key breakthrough of this project was the research team’s development of a cost-effective production method at application-relevant quantities. The copper and rubber raw materials start at about a dime per square meter with the costs reduced further by economies of scale, according to the study.

The team’s fabrication technique involves depositing a copper film onto a reusable substrate such as aluminum foil and then spraying multiple polymer layers onto the copper film, all of which can be done in “nearly any batch size imaginable.”

“The combined manufacturing strategy that we have now perfected in our lab is a real game-changer,” says Gorodetsky. “We have been working with cephalopod-inspired adaptive materials and systems for years but previously have only been able to fabricate them over relatively small areas. Now there is finally a path to making this stuff roll-by-roll in a factory.”

Coffee composites
The developed strategy and economies of scale should make it possible for the composite material to be used in a wide range of applications, from the coffee cup cozy up to tents or in any container in which tunable temperature regulation is desired.

The research has proven cephelapod skins can be used for packaging on an industrial scale.The invention has a high rate of environmental sustainability, says lead study author Mohsin Badshah, a former UC Irvine postdoctoral scholar in chemical and biomolecular engineering. “The composite material can be recycled in bulk by removing the copper with vinegar and using established commercial methods to repurpose the remaining stretchable polymer,” he explains.

The team conducted universally relatable coffee cup testing in their laboratory on the UC Irvine campus, where they proved they could control the cooling of the coffee. They were able to accurately and theoretically predict and then experimentally confirm the changes in temperature for the beverage-filled cups.

The team also achieved a 20-fold modulation of infrared radiation transmittance and a 30-fold regulation of thermal fluxes under standardized testing conditions. The stable material even worked well for high levels of mechanical deformation and after repeated mechanical cycling.

Temperature control
Gorodetsky says there is “an enormous array of applications for this material.”

“Think of all the perishable goods that have been delivered to people’s homes during the pandemic. Any package that Amazon or another company sends that needs to be temperature-controlled can use a lining made from our squid-inspired adaptive composite material. Now that we can make large sheets of it at a time, we have something that can benefit many aspects of our lives.”

Last year, Amazon came under criticism for using frozen plastic bottles to maintain cool temperatures in food packs. Greenpeace labeled the project a “greenwashing” ploy, in which yet more plastic is being produced and wasted.

By Louis Gore-Langton

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